When turbine-powered aircraft land, the wheel brakes and the imposed aerodynamic drag loads (e.g., flaps, spoilers, etc.) of the aircraft may not be sufficient to achieve the desired stopping distance. Thus, the engines on most turbine-powered aircraft include thrust reversers. Thrust reversers enhance the stopping power of the aircraft by redirecting the engine exhaust airflow in order to generate reverse thrust. When stowed, the thrust reverser typically forms a portion of the engine nacelle and forward thrust nozzle. When deployed, the thrust reverser typically redirects at least a portion of the airflow (from the fan and/or engine exhaust) forward and radially outward, to help decelerate the aircraft.
Various thrust reverser designs are commonly known, and the particular design utilized depends, at least in part, on the engine manufacturer, the engine configuration, and the propulsion technology being used. Thrust reverser designs used most prominently with turbofan engines fall into two general categories: (1) fan flow thrust reversers, and (2) mixed flow thrust reversers. Fan flow thrust reversers affect only the airflow discharged from the engine fan. Whereas, mixed flow thrust reversers affect both the fan airflow and the airflow discharged from the engine core (core airflow).
Fan flow thrust reversers are typically used on relatively high-bypass ratio turbofan engines. Fan flow thrust reversers include so-called “Cascade-type” or “Translating Cowl-type” thrust reversers. Fan flow thrust reversers are generally positioned circumferentially around the engine core aft of the engine fan and, when deployed, redirect fan airflow through a plurality of cascade vanes disposed within an aperture of a reverse flow path. Typically, fan flow thrust reverser designs include one or more translating sleeves or cowls (“transcowls”) that, when deployed, open an aperture, expose cascade vanes, and create a reverse flow path. Fan flow reversers may also include so-called pivot doors or blocker doors which, when deployed, rotate to block the forward thrust flow path.
In contrast, mixed flow thrust reversers are typically used with relatively low-bypass ratio turbofan engines. Mixed flow thrust reversers include so-call “Target-type,” “Bucket-type,” and “Clamshell Door-type” thrust reversers. These types of thrust reversers typically employ two or more pivoting doors that rotate, simultaneously opening a reverse flow path through an aperture and blocking the forward thrust flow path. However, a transcowl type thrust reverser could also be configured for use in a mixed flow application. When the transcowl is deployed, the transcowl and clamshell door configuration simultaneously opens a reverse flow path through an aperture and blocks the forward thrust flow path. Mixed flow thrust reversers are necessarily located aft or downstream of the engine fan and core, and often form the aft part of the engine nacelle.
As may be readily appreciated, it is undesirable to accidentally switch from forward thrust to reverse thrust; therefore, the thrust reverser designs generally employ a locking system to ensure that unplanned deployment of the thrust reverser is extremely improbable. A general locking system may comprise at least two, but often three or more locking elements, each locking element individually capable of retaining the thrust reverser in its stowed position. It is desirable that each locking element be independent of the others, so that a failure affecting one lock does not simultaneously affect the other locks. It is also desirable for the locking system to include a means for detecting locking system failures or malfunctions, so that they can be annunciated and repaired in a timely manner.
Emerging aircraft designs require locking methods and systems that provide improved detection of locking failures. Furthermore, other desirable features and characteristics of the present invention will be apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.